Switch locking means for portable electric tools



April 4, 1950 E. P. TURNER ET AL 2,503,226

SWITCH LOCKING MEANS FOR PORTABLE ELECTRIC TOOLS Filed Sept. 13, 1947 INVENTORS [agar R Turner BY Reynold fizz ape 4 Patented Apr. 4, 1950 SWITCH LOCKING MEANS FOR PORTABLE ELECTRIC TOOLS Edgar P. Turner, Fanwood, and Reynold Happe,

Pittstown, N. J assignors to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application September 13, 1947, Serial N 0. 773,813

7 Claims. 1

This invention relates to locking devices for electric switches of the type which are used to control the motors of electrically driven tools, such, for example, as portable electric drills.

In portable electric tools it is customary to provide control, or so-called off and on, switches and so to locate such switches, relative to the handles of the tools, that they may be readily actuated by the operator without moving his hand from its normal holding or operating position. One form of switch which is commonly used in tools of this nature is one in which the switch is normally biased to an open or off position and is maintained in closed or on position by the finger of the user, usually through the medium of a, suitable trigger.

For certain operations it is desirable that the motor run continuously for a considerable time and, to obviate the necessity of the user manually holding the switch closed, various means heretofore have been provided for locking the switch in its closed or on position in opposition to its natural bias.

Th present invention has as a primary object to provid improved and simplified means for locking a motor control switch in its closed or on position.

Another object of the invention is to provide an improved switch locking means adapted for use in connection with a unitary switch assembly such, for example, as that shown in United States patent of R. Happe, No. 2,405,827, August 13, 1946.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations, and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

Fig. 1 is a side elevation, partly in section, of a portion of a portable electric tool embodying the present invention.

Fig. 2 is a vertical sectional view taken on the line 22 of Fig. 1, showing the switch-locking means in its ineffective position.

Fig. 3 is a view similar to Fig. 2 but with the switch-locking means in its effective position in which it maintains the switch closed to effect continuous operation of the motor with which the tool is equipped.

.Fig. 4 is a horizontal sectional view taken on the line 44 of Fig. 3.

Fig. 5 is a perspective view of a unitary switch assembly with the present improved switch-locking means applied thereto.

Referring more specifically to the drawings, the invention is disclosed as embodied in a portable electric tool comprising a frame I, housing an electric motor, not shown, a hollow pistol-grip handle 2 having a slot 2 in its forward wall, and a motor-control switch unit U mounted in said handle. The switch unit may be of the type disclosed in the above mentioned patent to R. Happe, No. 2,405,827 including a supporting member 3 comprising a plate 4, for closing the lower end of the handle, an upstanding slotted wall portion 5 which fits within the slot 2 and pivotally supports, at p, a switch-actuating lever, preferably in the form of a trigger 6 having a finger-piece l, and a stepped block portion 8 upon which is secured, by a bracket 9, the vertically disposed body portion ID of the motor control switch. The finger piece 1 also is located within the slot 2 in the forward wall of the handle 2. Current-conducting wires a and b, which are adapted to be connected with any suitable source of electricity, are connected to the lower end of the portion l0 and spring contacts 0 and d are secured to the upper end thereof. The contacts 0 and d frictionally engage complemental contacts, as e, provided by the motor. Current flow through the switch is controlled by a suitable circuit making and breakin device including a lever I I fulcrumed on a pin 1 in the bracket 9 and normally biased to a circuit breaking position (shown in full lines in Fig. 1) by a spring l2 surrounding the pin 1 and engaging the bracket 9 and the lever II, as shown most clearly in Fig. 4. The portion ID of the switch and the leads connected thereto may be enclosed within an insulating wrapping l3. The switch lever II is formed at its free end as a ball M which tracks a groove IS in the rear edge of the finger-piece 'l of the trigger 6. Pressure of the ball M on the trigger 6, under the influence of the spring 12, normally biases the trigger 6 to its outermost or circuit breaking position illustrated in full lines in Fig. 1.

To start the motor, the user pulls the trigger 6 to the position indicated in dotted lines in Fig. 1, thereby shifting the switch lever I l to its circuit closing position also indicated in dotted lines in Fig. 1. So long as the trigger 6 and lever II are maintained in this position the motor will continue to run. Inasmuch as the switch may be-of conventional form and its specific construction forms no part of the present invention further illustration and description thereof is deemed unnecessary.

"When it is desired to maintain the circuit closed, to effect continuous running of the motor, without manually holding the trigger depressed in opposition to the spring l2, the user actuates the improved switch locking means which constitutes the present invention. This means comprises a vertically disposed leaf spring I6, having, at its lower end, an offset portion I! which is secured, by a screw [8, to the block portion 8 of the supporting member 3. The spring iii normally occupies the position shown in Fig. 2 i. e. flatwise with respect to the switch actuating-lever 6 and with its head portion it out of the path.

of movement of the finger piece T and bearing against the head w of a plungerpin t9 slidingly mounted in a smooth straight hole or bore h in the front wall of the handle 2. The spring It may be biased to the switch locking position shown in Fig. 3, after the trigger has been shifted to the circuit closing position illustrated in dotted lines in Fig. 1',- by pressure applied to the outer rounded end of theplunger i9; as, for example; by the thumb of the user. In the positio'n shown in Fig. 3', the head i6 is located in a cavityzil formedi the finger-piece l of the trigger 6; With the spring in this position, pressure onthe finger-piece may be relieved whereupon the spring i 2 w-illswing the trigger outwardly untilthe-head lfi of 'the'spring lS-is engaged by the abutment wall 20*01 thecavity 2! as shown in Fig. 4*. This movementis slight and not suff1- cient to permit opening of the switch. A retainingflange 2t also'is provided by a wall of the" cavity 202 This flange'overhangs the side of the head W o-f'theleaf spring'and serves as a man- I uall'y releasable latch which prevents the spring frommeturning to its outermost position. When it is desired to open the-switch to-stcp the motor the trigger isagain pulled inwardly to release the-flangezi from the head it whereupon the spring tdmoves outwardly to the position shown in Fig. 2 pushing the plunger l-9- outwardly with it; By then relieving the pressure on the trigger, the trigger'willbe moved outwardly'bythespring F2 and the motor will be stopped;

Itvv-ill be noted; that this switch locking and releasing means comprises only three elements, viz-.- the spring I63 its attaching screw IS" and the plunger I9- all of which maybe easily and cheaply manufactured and assembled; Particularatten tionis called to' the fact that no separate spring andno separate housing means is required for the plunger H; the switch locking element l6 affording the-pressureto shift the plunger outwardly and a plain hole drilled in the handle serving ahousing for the plunger.

It" will alsobe" noted that this construction permits ready removal of the switch unit from the handleforinspection or repair without any special consideration of means; the-spring lE-being removable with the unit and the plunger ii! merely remaining in the hole It until the switchunit is reinserted into thehandle;

Having thus set forth the nature of the invention; what we claim herein is:

l; A locking device fora switch unit having a shiftable switch-actuating lever norrnaily biased to one of two predetermined positions and provi'ded with an abutment surface; comprising a leaf spring mounted fia'avise" adjacent said lever and normally out of" the path of movement of said abutment, and means including-a manually sl' idabl'e -plunger' engaging said lever and operable when said lever is in one of said predetermined the switch locking positions in opposition to its normal bias, to de flect said leaf spring into the path of movement of said abutment surface to hold said lever against return movement to its other predetermined position.

2. A locking. device for a switchunit having a shiftable switcheactuatinglever normally biased to a circuit breaking position and provided with a cavity a wall of which affords an abutment surface-anda retaining flange; comprising a leaf spring. mounted flatwise adjacent said lever and having an end portion adapted to enter the cavity insaid switch actuating-lever when said lever is in its circuit closing position, and a manually slidable plunger adapted to engage said leaf spring to deflect said end portion into said cavity and into the pathv of movement of said abutment surface to hold said lever against movement to its other predetermined position, said retaining flange engaging said leaf spring to maintain it insa-id cavity and in the path of movement of said abutment.

35 A locking device for a switchunit having a shiftableswitch-actuating lever normally biased to a circuit opening position but shif-table to a circuit" closing position and provided with an abutmentsurf'ace; comprising a leaf spring mounted flatwi'se adjacent said lever, a manually operable member constructed and arranged to deflect said leaf spring into thepath of movement-of said abutment surface to cause thespring to hold the lever in its circuit closing positionin opposition to its normal bias, and a manually releasable latch device carried by said lever" and engaging said spring to maintain it in leverholding position.

4a In an electrictoolhaving a casing, a handle having a wall-provided with an aperture, an elec tric motor in'saidcasing and a motor-controlling switch unit mounted in said handle and havinga shiftab'le switch-actuating lever normally biased to' one of two predetermined positions'and provided with an abutment surface; theimprove men-twhich consists the provision ofa locking device forsaid switch-actuating lever comp-rising a leaf spring mounted on' said switclr unit and arranged flatwise adjacent said level" and normallymai'ntained out of thepathof movement of said abutment surface, and'a manually operable plunger slida'b-ly mounted inthe aperture in said" handle and engaging said leaf spring for deflecting it into the path of movement of said abut-' ment surface thereby to obstruct the normal return movement of said lever;

5. Ir'ran electric tool havinga casing; a hollow" handle having'a side wallprovided with a straight bore and a front wall provided with a slot, an electric motor in said casing and a motor-controlling switch rrnit removably mounted in said" hollow handle and having a shiftable' SWlt'Chactuating lever normally biased to oneoftwo'pre determined positions and provided with an abutment surface and a retaining flange; the improvement which consistes in'the' provision of'a; locking device for said snatch-actuating leverw comprising a leaf spring mounted on said switch" unit and arranged" fiatwise adjacent said lever and having an end portion normally maintained out ofthe' pathof movement of said abutment surface and retainingfiange, and a manuallyop erable cylindrical plungerslida'bly mountecl' intthe' aperture in said, handle and having a headlocat'ed insaitf slot and engaging said leaf spring. for deflecting it into the path' of movement of 75-saidabutment'surface and to a position behind April 11, 1950 A. COHEN 2,503,243

smcmonymurc RELAY Filed Dec. 11, 1945 Yl/I/ INVENTOR. A/t/f Cohen 

